Front Up-Down Position Sensor:

Remove the driver's power seat. See POWER HEATED SEATS .
NOTE: Be careful to not scratch the interior trim.
Disconnect the 5P connector from the front up-down position sensor and the 20P connector from the power seat control unit.
Check for continuity between the No. 4 terminal of the front up-down position sensor and A11 terminal of the power seat control unit.

Fig 1: Checking Continuity At Power Seat Control Unit 20P Connector A
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES -Go to step 4.
2. NO -Repair open in the WHT/BLK wire.
Check for continuity between the No. 5 terminal of the front up-down position sensor and A12 terminal of the power seat control unit.

Fig 2: Checking Continuity Between No. 5 Terminal Of Front Up-Down Position Sensor And A12 Terminal Of Power Seat Control Unit
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES -Go to step 5.
2. NO -Repair open in the GRN/BLK wire.
Reconnect the 5P and 20P connectors.
Check for voltage between the No. 1 terminal of the front up-down position sensor and body ground.

Fig 3: Checking Voltage Between No. 1 Terminal Of Front Up-Down Position Sensor And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 5 V?
1. YES -Go to step 7.
2. NO -Repair the open or a short to ground in the BRN wire.
Check for voltage pulse between the No. 5 terminal of the front up-down position sensor and body ground when the front up-down switch moves up and down.

Fig 4: Checking For Voltage Pulse
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Does voltage pulse from 0 to about 5 V alternately?
1. YES -Replace the power seat control unit.
2. NO -Check for a short in the wire. If the wire is OK, faulty front up-down position sensor; replace the front up-down motor assembly.